"The sauropod's neck became what the hook-and-ladder is to a firefighter: a means of extended reach that could be critical. It gave these animals an ability to graze a much wider radius of ground vegetation without moving a step."

Also, I never knew that sauropods didn't have molars. They quickly bite and swallow as much as possible, and let their immense gut break it down over many days.

How does that work? I've seen suggestions that the bones of the neck lock together to form a rigid structure, so that the whole thing is cantilevered off the shoulders and chest without muscles needing to do work to support it. But if that's the case it doesn't seem like it would be flexible, which means the animal could only graze along the circumference of a circle without moving, not the whole area in front of itself.

Were their necks flexible and muscular so that they could graze a large area without moving, or rigid and self-supporting so that they didn't need to do as much work, but had to move more to graze?